A fishing vessel assisting in the search for 46 crewmen of the 1,200-ton ship Cheonan, which sunk late last month, goes down. The nine fishermen on board are presumed dead.

A South Korean naval unit searches for survivors from the Cheonan. (Associated Press )

Reporting from Seoul — Heaping more tragedy on an already grieving South Korea, a fishing vessel assisting in the search for 46 crewmen of a sunken naval boat went down Saturday, and the nine on board were presumed dead.

As the South Korean coast guard retrieved the bodies of two of the fishermen,divers found the first corpse from the 1,200-ton navy ship Cheonan, which sank late last month after an explosion. Fifty-eight crew members, including the captain, were rescued.

The body was discovered near the ship's mess hall, the Joint Chiefs of Staff said.

The circumstances of the navy ship's sinking remained a mystery, one that has been compounded by other losses. A military diver died after losing consciousness as he scouted the hull of the boat.

Salvage operations were set to begin Sunday after families of the missing sailors requested that the military halt underwater searches for bodies. "We have made the decision on fears that more lives will be lost in the underwater operation," said Lee Jung-guk, head of a committee made up of relatives of missing Cheonan sailors.

The Cheonan broke in two after the explosion, which occurred near the contested sea border between North and South Korea. There has been no confirmation of North Korean involvement in the incident.

Although many believe the boat may have struck a Korean War-era mine, Defense Minister Kim Tae-young told the South Korean parliament Friday that the Cheonan was more likely struck by a torpedo.

He did not elaborate.

Officials have said the cause of the sinking cannot be determined until the ship is recovered, which could take weeks.